clang/test/SemaCXX/underlying_type.cpp

   1 // RUN: %clang_cc1 -triple %itanium_abi_triple -ffreestanding -fsyntax-only -verify -std=c++11 %s
   2
   3 #include "limits.h"
   4
   5 template<typename T, typename U>
   6 struct is_same_type {
   7   static const bool value = false;
   8 };
   9 template <typename T>
  10 struct is_same_type<T, T> {
  11   static const bool value = true;
  12 };
  13
  14 __underlying_type(int) a; // expected-error {{only enumeration types}}
  15 __underlying_type(struct b) c; // expected-error {{only enumeration types}}
  16
  17 enum class f : char;
  18 static_assert(is_same_type<char, __underlying_type(f)>::value,
  19               "f has the wrong underlying type");
  20
  21 enum g {d = INT_MIN };
  22 static_assert(is_same_type<int, __underlying_type(g)>::value,
  23               "g has the wrong underlying type");
  24
  25 __underlying_type(f) h;
  26 static_assert(is_same_type<char, decltype(h)>::value,
  27               "h has the wrong type");
  28
  29 template <typename T>
  30 struct underlying_type {
  31   typedef __underlying_type(T) type; // expected-error {{only enumeration types}}
  32 };
  33
  34 static_assert(is_same_type<underlying_type<f>::type, char>::value,
  35               "f has the wrong underlying type in the template");
  36
  37 underlying_type<int>::type e; // expected-note {{requested here}}
  38
  39 using uint = unsigned;
  40 enum class foo : uint { bar };
  41
  42 static_assert(is_same_type<underlying_type<foo>::type, unsigned>::value,
  43               "foo has the wrong underlying type");
  44
  45 namespace PR19966 {
  46   void PR19966(enum Invalid) { // expected-note 2{{forward declaration of}}
  47     // expected-error@-1 {{ISO C++ forbids forward references to 'enum'}}
  48     // expected-error@-2 {{variable has incomplete type}}
  49     __underlying_type(Invalid) dont_crash;
  50     // expected-error@-1 {{cannot determine underlying type of incomplete enumeration type 'PR19966::Invalid'}}
  51   }
  52   enum E { // expected-note {{forward declaration of 'E'}}
  53     a = (__underlying_type(E)){}
  54     // expected-error@-1 {{cannot determine underlying type of incomplete enumeration type 'PR19966::E'}}
  55     // expected-error@-2 {{constant expression}}
  56   };
  57 }
  58
  59 template<typename T> void f(__underlying_type(T));
  60 template<typename T> void f(__underlying_type(T));
  61 enum E {};
  62 void PR26014() { f<E>(0); } // should not yield an ambiguity error.
  63
  64 template<typename ...T> void f(__underlying_type(T) v); // expected-error {{declaration type contains unexpanded parameter pack 'T'}}
  65
  66 namespace PR23421 {
  67 template <class T>
  68 using underlying_type_t = __underlying_type(T);
  69 // Should not crash.
  70 template <class T>
  71 struct make_unsigned_impl { using type = underlying_type_t<T>; };
  72 using AnotherType = make_unsigned_impl<E>::type;
  73
  74 // also should not crash.
  75 template <typename T>
  76 __underlying_type(T) ft();
  77 auto x = &ft<E>;
  78 }